Sent folder doesn't show up in Thunderbird

I have three different Gmail email accounts set up in Thunderbird. On the left side of the screen, there's the pane that shows your email accounts and folders. The two of my three Gmail accounts that are working correctly, show a folder entited: [Gmail] When I click to expand the the [Gmail] folder, it contains the following folders: Drafts, Sent Mail, All Mail, Spam, Trash. Why would one (of three) Gmail accounts not show the Sent folder (or more importantly, not show the [Gmail] folder that contains Drafts, Sent Mail, etc)? Please help!